JPWO2013038649A1 - Light emitting module - Google Patents

Abstract

In the light emitting module 10, the second phosphor layer 26 includes a red phosphor so that the wavelength of the light after wavelength conversion of the second phosphor layer 26 is longer than that of the first phosphor layer 24, and the first phosphor. Layer 24 includes a blue phosphor and a yellow-green phosphor. The 1st fluorescent substance layer 24 is formed in the irradiation area | region of the light from LED chip 22, converts the wavelength of the light from LED chip 22, and radiate | emits it from the output surface 24a. A part of the second phosphor layer 26 is formed in a non-direct irradiation region where light is not irradiated from the LED chip 22 and light is irradiated from the first phosphor layer 24, and a portion formed in the non-direct irradiation region The wavelength of the light from the first phosphor layer 24 is converted and emitted from the emission surface 24a through the first phosphor layer 24.

Description

  The present invention relates to a light emitting module, and more particularly to a light emitting module including a phosphor layer that emits light after wavelength conversion.

  In recent years, the use of semiconductor light emitting devices such as LEDs (Light Emitting Diodes) has been rapidly expanding such as vehicle headlamps and general lighting. When white light is obtained using such a semiconductor light emitting element, the light emitting surface of the semiconductor light emitting element that emits light such as blue light, near ultraviolet light, or short wavelength visible light is opposed to the light emitting surface of the semiconductor light emitting element. An optical wavelength conversion member that emits light of a wavelength is generally disposed. As a white light-emitting LED light-emitting device, a device in which a yellow phosphor that emits yellow light when excited by blue light is disposed facing a light emitting surface of a blue light-emitting LED is known.

  Here, in order to obtain white light with high color rendering properties, the wavelengths of the three primary colors of blue, green, and red are required. For this reason, in the white LED light-emitting device which combined the above blue LED and yellow fluorescent substance, there exists room for improvement in this color rendering property. In order to improve the color rendering, the light wavelength conversion member includes a blue phosphor, a yellow phosphor, and a red phosphor, and is emitted from a semiconductor light emitting device that emits light having a peak wavelength in a range of 370 nm to 470 nm. There has been proposed a white light-emitting lamp that emits white light by exciting a light wavelength conversion member with light (for example, see Patent Document 1).

Special table 2008-096545 gazette

  However, since the red phosphor absorbs blue light and yellow light having a shorter wavelength than red light and emits red light, the longer the optical path length from the emission surface to emission, the easier it is for the emission light to be reddish. For this reason, in the exit surface of the light wavelength conversion member, a portion that is farther from the light emitting surface of the light emitting element may emit more reddish light than a nearby portion. Accordingly, there is a strong demand for the development of a light wavelength conversion member that makes the color of light emitted from the emission surface uniform.

  Accordingly, the present invention has been made to solve the above-described problems, and an object of the present invention is to provide an optical wavelength conversion member that achieves high color rendering and makes the color of light emitted from the exit surface uniform. There is to do.

  In order to solve the above problems, a light emitting module according to an aspect of the present invention includes a first phosphor layer and a second phosphor layer having a longer wavelength of light after wavelength conversion than the first phosphor layer. . The first phosphor layer is formed in the irradiation region of light from the light emitting element, wavelength-converts the light from the light emitting element and emits it from the emission surface, and the second phosphor layer is irradiated with light from the light emitting element. First, at least a part is formed in a predetermined region irradiated with light from the first phosphor layer, and the portion formed in the predetermined region converts the wavelength of light from the first phosphor layer and passes through the first phosphor layer. The light exits from the exit surface.

  According to this aspect, the first phosphor layer is first compared to the case where the mixed phosphor layer in which the phosphor contained in the first phosphor layer and the phosphor contained in the second phosphor layer are mixed is provided. Thus, it is possible to avoid the situation where the wavelength-converted light is wavelength-converted again by the phosphor contained in the second phosphor layer in the first phosphor layer. For this reason, the color of the emitted light can be made uniform regardless of the length of the optical path length of the light in the first phosphor layer. In the first phosphor layer, light is emitted also in the direction in which the phosphor is directed toward the emission surface, but light is also emitted in other directions. According to this aspect, part of such light can be wavelength-converted again by the second phosphor layer. For this reason, the light that has been wavelength-converted again by the second phosphor layer can be mixed with the light that travels in a direction other than the exit surface in the first phosphor layer, and this also shortens the optical path length of the light. Regardless of this, the color of the emitted light can be made uniform.

  At least a part of the second phosphor layer is formed between a plane including the light emitting surface of the light emitting element and a mounting surface of the substrate on which the light emitting element is mounted. The first phosphor layer is formed from the second phosphor layer. May also be formed on the light emitting direction side of the light emitting surface.

  In the first phosphor layer, light directed toward the mounting surface of the substrate is also emitted. According to this aspect, part of such light can be wavelength-converted again by the second phosphor layer. For this reason, light that has been wavelength-converted again by the second phosphor layer can be mixed with light that travels from the first phosphor layer toward the mounting surface of the substrate, and can be output regardless of the length of the optical path length of the light. The color of the incident light can be made uniform.

  The second phosphor layer may be formed from the mounting surface to the light emitting direction side from the plane including the light emitting surface of the light emitting element so as to cover the light emitting surface of the light emitting element. According to this aspect, part of the light traveling toward the first phosphor layer can be wavelength-converted by the second phosphor layer. For this reason, the light emitted from the first phosphor layer can appropriately include the light whose wavelength is converted by the second phosphor layer.

  The plurality of light emitting elements are arranged so that each light emitting surface is included in one plane while being separated from each other, and the second phosphor layer is arranged in a region between the plurality of light emitting elements when viewed from the light emitting surface side. The first phosphor layer is formed on the light emitting direction side of the light emitting surface with respect to the light emitting surface, and the first phosphor layer is formed on the light emitting surface side of the light emitting surface. May be. According to this aspect, the uneven color of the emitted light in the area between the plurality of light emitting elements can be suppressed.

  ADVANTAGE OF THE INVENTION According to this invention, the light wavelength conversion member from which the color of the light radiate | emitted from an output surface becomes uniform can be provided, implement | achieving high color rendering properties.

(A) is a front sectional view of the light emitting module according to Example 1, and (b) is a top view of the light emitting module according to Example 1. FIG. It is the figure which expanded a part of front sectional view of the light emitting module which concerns on Example 1. FIG. (A) is a front sectional view of the light emitting module according to Comparative Example 1, and (b) is a top view of the light emitting module according to Comparative Example 1. In the light emitting module which concerns on the comparative example 1, it is a figure which shows a measurement result when measuring chromaticity, moving a measurement point from the reference point PO to the measurement direction D1. It is sectional drawing of the light emitting module for demonstrating the mechanism in which the color nonuniformity produces in the comparative example 1. FIG. In the light emitting module which concerns on Example 1, it is a figure which shows a measurement result when measuring chromaticity, moving a measurement point from the reference point PO to the measurement direction D1. It is sectional drawing of the light emitting module for demonstrating the mechanism in which color nonuniformity is suppressed in Example 1. FIG. (A) is a front sectional view of the light emitting module according to Example 2, and (b) is a top view of the light emitting module according to Example 2. (A) is a front sectional view of the light emitting module according to Comparative Example 2, and (b) is a top view of the light emitting module according to Comparative Example 1. In the light emitting module which concerns on the comparative example 2, it is a figure which shows a measurement result when measuring chromaticity, moving a measurement point from the reference point PO to the measurement direction D2. In the light emitting module which concerns on Example 1, it is a figure which shows a measurement result when measuring chromaticity, moving a measurement point from the reference point PO to the measurement direction D2. It is a figure which shows each color rendering index Ra of the light emitting module which concerns on Example 2, and the light emitting module which concerns on the comparative example 2. FIG. FIG. 13A is a diagram schematically showing variations in the color of light emitted from the light emitting module when the concentration distribution of the phosphors in the second phosphor layer is uniform, and FIG. 13B is a diagram illustrating the second fluorescence. It is a figure which shows typically the dispersion | variation in the color of the irradiation light of the light emitting module at the time of changing the density | concentration of the fluorescent substance of a body layer. It is a partial cross section figure of the light emitting module which shows the modification of a 2nd fluorescent substance layer. FIG. 15A to FIG. 15F are a perspective view, a cross-sectional view, or a top view showing an example of the shape of the second phosphor layer. It is a partial cross section figure of the light emitting module which shows the modification of a 2nd fluorescent substance layer. FIG. 17A and FIG. 17B are perspective views showing a modification of the entire phosphor layer in the light emitting module according to Example 1. FIG. FIG. 18A to FIG. 18E are a perspective view, a cross-sectional view, or a top view showing a modification of the entire phosphor layer in the light emitting module according to the second embodiment. FIG. 19A is a cross-sectional view of a light emitting module in which the side surface of the second phosphor layer is covered with the first phosphor layer, and FIG. 19B is a diagram illustrating the outer side of the second phosphor layer facing outward. 2 is a cross-sectional view of a light emitting module in which the thickness of the phosphor layer is reduced, FIG. 19C is an enlarged view of a region C shown in FIG. 19B, and FIG. 19D is the first view shown in FIG. It is sectional drawing of the light emitting module which made the thickness of the 2nd fluorescent substance layer thin toward the outer side in the outer peripheral part of 2 fluorescent substance layers. It is sectional drawing which shows an example of the light emitting module with which the ratio of the thickness of a 1st fluorescent substance layer and the projection area of a 2nd fluorescent substance layer is substantially the same in several directions. It is sectional drawing which shows the other example of the light emitting module whose ratio of the thickness of the 1st fluorescent substance layer and the projected area of a 2nd fluorescent substance layer is substantially the same in several directions.

  Hereinafter, examples of the present invention will be described in detail with reference to the drawings, in comparison with comparative examples.

(Example 1)
FIG. 1A is a front sectional view of the light emitting module 10 according to the first embodiment, and FIG. 1B is a top view of the light emitting module 10 according to the first embodiment. The light emitting module 10 includes an LED unit 12 and a phosphor unit 14.

  The LED unit 12 includes a substrate 20 and a plurality of LED chips 22. The substrate 20 has an elongated rectangular outer shape. The plurality of LED chips 22 are mounted in advance on the mounting surface 20a of the substrate 20 so as to be arranged in a line at equal intervals in the extending direction of the substrate 20. At this time, not only the LED chip 22 but also a bonding wire, a Zener diode, and a submount as needed are mounted.

  In the first embodiment, the plurality of LED chips 22 are arranged so that the interval is 8 mm. Of course, the interval between adjacent LED chips 22 is not limited to 8 mm. Thus, the plurality of LED chips 22 are arranged such that each light emitting surface 22a is included in one plane while being separated from each other. The plurality of LED chips 22 may be mounted on the substrate 20 so that the planes including the light emitting surface 22a are different from each other.

  The LED chip 22 has a 1 mm square square light emitting surface 22a. The back surface of the light emitting surface 22 a is mounted on the mounting surface 20 a of the substrate 20. For this reason, all the light emitting surfaces 22a of the plurality of LED chips 22 are parallel to the mounting surface 20a. In Example 1, five LED chips 22 were mounted on the substrate 20. Of course, the number of LED chips 22 is not limited to five, and a plurality of LED chips 22 other than five may be mounted on the substrate 20. Moreover, the light emitting module 10 is not limited to the one in which the plurality of LED chips 22 are arranged in a straight line, and the plurality of LED chips 22 may be arranged in a two-dimensional direction parallel to the mounting surface 20a. In addition, the mounting surface 20a of the board | substrate 20 is uneven | corrugated shape so that the plane containing the light emission surface 22a of the some LED chip 22 may mutually differ, and it may be mounted in the concave surface and the convex surface. Moreover, the planes including the light emitting surfaces 22a of the plurality of LED chips 22 may be made different from each other by changing the thickness of a submount or the like on the mounting surface a of the substrate 20.

  The LED chip 22 is a semiconductor light emitting element, and in the first embodiment, one that emits short-wavelength visible light or near ultraviolet light is employed. Note that the LED chip 22 is not limited to this, and may emit blue light, for example.

  The phosphor unit 14 has a first phosphor layer 24 and a second phosphor layer 26. The first phosphor layer 24 includes a blue phosphor (not shown) and a yellow-green phosphor (not shown). This blue phosphor is excited by short-wavelength visible light or near-ultraviolet light and emits blue light. This yellow-green phosphor emits yellow-green light when excited by short-wavelength visible light or near-ultraviolet light. In place of or in addition to this yellow-green phosphor, a green phosphor that emits green light when excited by short-wavelength visible light or near ultraviolet light, or a yellow-amber phosphor that emits yellow to amber light is used. Also good. The second phosphor layer 26 includes a red phosphor. The red phosphor is excited by short wavelength visible light or near-ultraviolet light and emits red light. Therefore, the second phosphor layer 26 has a longer wavelength of light after wavelength conversion than the first phosphor layer 24.

  The second phosphor layer 26 is directly applied to the mounting surface 20a of the substrate 20 on which the LED chip 22 is mounted. The first phosphor layer 24 is further applied on the upper surface of the second phosphor layer 26. Thus, the second phosphor layer 26 and the first phosphor layer 24 are laminated in this order from the mounting surface 20a of the substrate 20.

  Hereinafter, a specific manufacturing method of the light emitting module 10 will be described in detail. The light emitting module 10 was manufactured so that the chromaticity coordinates would be (0.41, 0.39), assuming replacement of a fluorescent lamp.

First, five LED chips 22 were mounted on the substrate 20 on which a circuit pattern was formed. The arrangement of the LED chip 22 at this time is as described above. The red phosphor paste was prepared by dispersing the red phosphor in a transparent resin or paint. As the red phosphor at this time, a red-emitting nitride phosphor represented by the following general formula,
Formula _{(Ca 1-X-y Sr} X) AlSiN 3: Eu 2+ y
Was used. As the red phosphor, a red-emitting nitride phosphor represented by the following general formula,
General formula (Ca _1-x Eu _x ) Si ₅ N ₈
May be used. Of course, the red phosphor is not limited to this.

  The phosphor concentration of the red phosphor paste was 10 vol%. The phosphor concentration of the red phosphor paste may be any value between 0.5 and 15 vol%. Resins for sealing the phosphor 1 are silicones such as dimethyl silicone, phenyl silicone and acrylic silicone, sol-gel (silica, titania, etc.), epoxy, acrylic, polyurethane, polyester, PET (polyethylene terephthalate). , Fluoropolymer, melamine, PVA (polyvinyl alcohol), or PVB (polyvinyl butyral) can be used.

  The red phosphor paste thus adjusted was applied to the mounting surface 20a of the substrate 20 on which the LED chip 22 was mounted. At this time, the second phosphor layer 26 was applied so that the thickness was 80 μm. In addition, the thickness of the 2nd fluorescent substance layer 26 may be any value of 20-200 micrometers. Specifically, a dam having a predetermined thickness was prepared on the substrate 20 in advance, and a red phosphor paste was poured into the dam by a method such as dispensing or potting. The applied red phosphor paste was semi-cured or cured under conditions suitable for the resin material used.

Next, a mixed phosphor in which a blue phosphor and a yellow-green phosphor were mixed was prepared. The mixing ratio at this time may be appropriately selected in the range of blue phosphor: yellow-green phosphor = 20: 80 to 65:35 in terms of mass ratio. For example, in this embodiment, blue phosphor: yellow-green fluorescence. Body = 60: 40. This mixed phosphor was dispersed in a silicone resin to prepare a mixed phosphor paste. As the blue phosphor at this time, a blue phosphor represented by the following general formula,
Formula ^{_{M 1 a (M 2 O 4}} ) b X c: Re d
^{(M 1} is .M ² may be substituted Ca, Sr, and essential one or more kinds of Ba, some Mg, Zn, Cd, K, Ag, to any element of the group consisting of Tl is P is essential, and a part thereof can be replaced with any element of the group consisting of V, Si, As, Mn, Co, Cr, Mo, W, and B. X is at least one halogen element, and Re is Eu ^{2+ represents} at least one rare earth element, or Mn, where a is 4.2 ≦ a ≦ 5.8, b is 2.5 ≦ b ≦ 3.5, and c is 0.8 <c <. 1.4, d is in the range of 0.01 <d <0.1)
Was used. Of course, the blue phosphor is not limited to this.

In addition, as a blue phosphor, a blue phosphor represented by the following general formula,
General formula M ¹ _1-a MgAl ₁₀ O ₁₇ : Eu ²⁺ _a
(M ¹ is at least one element selected from the group consisting of Ca, Sr, Ba, and Zn, and a is in the range of 0.001 ≦ a ≦ 0.5)
May be used.

Further, as a blue phosphor, a blue phosphor represented by the following general formula,
General formula M ¹ _1-a MgSi ₂ O ₈ : Eu ²⁺ _a
(M ¹ is at least one element selected from the group consisting of Ca, Sr, Ba, and Zn, and a is in the range of 0.001 ≦ a ≦ 0.8)
May be used.

Further, as a blue phosphor, a blue phosphor represented by the following general formula,
General formula M ¹ _2-a (B ₅ O ₉ ) X: Re _a
(M ¹ is at least one element selected from the group consisting of Ca, Sr, Ba and Zn, X is at least one halogen element, and a is in the range of 0.001 ≦ a ≦ 0.5)
May be used.

Further, as the yellow-green phosphor, a yellow-green phosphor represented by the following general formula,
Formula _{(Ca1 -x-y-z-} w, Sr x, M II y, Eu z, M R w) 7 (SiO 3) 6 X 2
(M ^II is, Mg, shows the Ba or Zn, ^{M R} is .X showing a rare earth element or Mn are, Cl or, .x showing a more halogen element essentially including Cl, y, z are each 0.1 <x <0.7, 0 ≦ y <0.3 0 <z <0.4, 0 ≦ w <0.1)
Was used. This yellow-green phosphor is hardly excited by the blue light emitted from the blue phosphor described above. For this reason, even if this yellow-green phosphor and the above-described blue phosphor are mixed, the color uniformity of the emitted light is hardly lost. Needless to say, the yellow-green phosphor is not limited to this, and other yellow-green phosphors, yellow phosphors, and green phosphors may be used instead.

  The phosphor concentration of the mixed phosphor paste was 1.1 vol%. Note that the phosphor concentration of the mixed phosphor paste may be any value of 0.1 to 10 vol%, more preferably any value of 0.5 to 8 vol%.

  The mixed phosphor paste thus prepared was applied over the already applied red phosphor paste. At this time, the thickness of the first phosphor layer 24 was 4 mm. The thickness of the first phosphor layer 24 may be any value between 0.5 and 18 mm, more preferably any value between 0.5 and 5 mm.

  In this way, after the second phosphor layer 26 and the first phosphor layer 24 are applied to the mounting surface 20a of the substrate 20, heating is performed under any condition from 15 to 30 minutes at 80 ° C. to 60 minutes at 150 ° C. The light emitting module 10 was produced by curing.

  The light emitting module 10 according to Example 1 was turned on and the chromaticity distribution was measured. The light emitting module 10 is placed so that the plurality of LED chips 22 are arranged in the horizontal direction, and the measurement of chromaticity is started from the center of the second LED chip 22 from the left as a reference point PO. As shown in FIG. 1B, the measurement of chromaticity is repeated while moving the measurement point little by little from the reference point PO toward the center of the LED chip 22 adjacent to the right, and the fourth LED chip 22 from the left. The measurement was completed after measuring to the center of. Hereinafter, the moving direction of the measurement point is referred to as a measurement direction D1.

  FIG. 2 is an enlarged view of a part of a front sectional view of the light emitting module 10 according to the first embodiment. The LED chip 22 is mounted on the mounting surface 20 a of the substrate 20. Therefore, the light from the light emitting surface 22a does not directly reach the region between the flat surface including the light emitting surface 22a of the LED chip 22 and the mounting surface 20a. Hereinafter, this region is referred to as “non-direct irradiation region”. The non-direct irradiation region can also be referred to as a region between the side surfaces 22b of the plurality of LED chips 22.

  On the other hand, the red phosphor paste is applied to the mounting surface 20a, and the second phosphor layer 26 is formed. For this reason, the second phosphor layer 26 also exists in this non-direct irradiation region. Therefore, the second phosphor layer 26 in the non-direct irradiation region does not emit red light by direct light from the LED chip 22.

  In Example 1, the 2nd fluorescent substance layer 26 is formed from the mounting surface 20a to the light emission direction side of the light emission surface 22a rather than the plane containing the light emission surface 22a. Therefore, the second phosphor layer 26 is formed so as to cover the light emitting surface 22a. Therefore, a part of the second phosphor layer 26 is formed on the light emitting direction side from the plane including the light emitting surface 22a, and the other part is formed in the non-direct irradiation region. Note that the second phosphor layer 26 may be entirely formed in the non-direct irradiation region. That is, the 2nd fluorescent substance layer 26 may be formed from the mounting surface 20a to the mounting surface 20a side rather than the plane containing the light emission surface 22a.

  The first phosphor layer 24 is applied on the emission surface 26 a of the second phosphor layer 26. Therefore, the 1st fluorescent substance layer 24 is formed in the light emission direction side of the light emission surface 22a rather than the 2nd fluorescent substance layer 26. FIG. The 1st fluorescent substance layer 24 is formed in the irradiation region of the light from LED chip 22, changes the wavelength of light from LED chip 22 into yellowish green and blue, and emits it from an outgoing surface.

  In the above-mentioned non-direct irradiation region, light is not directly irradiated from the LED chip 22, while light from the first phosphor layer 24 is irradiated with light that is converted in wavelength and directed toward the mounting surface 20a. The second phosphor layer 26 is partially formed in the non-direct irradiation region, and the portion formed in the non-direct irradiation region converts the wavelength of light from the first phosphor layer 24 and passes through the first phosphor layer 24. The light exits from the exit surface 24a.

  In Example 1, the 2nd fluorescent substance layer 26 is formed from the mounting surface 20a to the light emission direction side of the light emission surface 22a rather than the plane containing the light emission surface 22a. Therefore, a part of the second phosphor layer 26 is formed so as to cover the light emitting surface 22a, and the other part is formed in the non-direct irradiation region. Hereinafter, in the second phosphor layer 26, a portion on the light emitting direction side from the light emitting surface 22a is referred to as a first layer 26b, and a portion on the mounting surface 20a side from the light emitting surface 22a, that is, a portion formed in a non-direct irradiation region. This is referred to as the second layer 26c. Note that the second phosphor layer 26 may be entirely formed in the non-direct irradiation region. That is, the 2nd fluorescent substance layer 26 may be formed from the mounting surface 20a to the mounting surface 20a side rather than the plane containing the light emission surface 22a.

(Comparative Example 1)
3A is a front sectional view of the light emitting module 50 according to Comparative Example 1, and FIG. 3B is a top view of the light emitting module 50 according to Comparative Example 1. Hereinafter, the same parts as those of the light emitting module 10 according to the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

The light emitting module 50 includes an LED unit 12 and a phosphor layer 52. The phosphor layer 52 includes the red phosphor, the yellow-green phosphor, and the blue phosphor used in the light emitting module 10. In order to prepare a mixed phosphor paste for forming the phosphor layer 52, first, a blue phosphor, a yellow-green phosphor, and a red phosphor in a mass ratio, blue phosphor: yellow-green phosphor: red fluorescence. Body = 57.9: 38.6: 3.5 to prepare a mixed phosphor. This mixed phosphor was dispersed in a silicone resin to prepare a mixed phosphor paste. The phosphor concentration of the mixed phosphor paste was 1.2 vol%. The mixed phosphor paste thus adjusted was applied onto the mounting surface 20a of the substrate 20 to form the phosphor layer 52. At this time, the thickness of the phosphor layer 52 was 4 mm.

(Experimental result 1)
FIG. 4 is a diagram illustrating a measurement result when the chromaticity is measured while moving the measurement point from the reference point PO in the measurement direction D1 in the light emitting module 50 according to the comparative example 1. Δcx and Δcy on the vertical axis indicate the amount of change in the color coordinates (cx, cy) in the CIE chromaticity coordinates with the CIE chromaticity at the reference point PO as a reference value.

  In FIG. 4, the locations where the distance from the reference point PO is 0 mm, 8 mm, and 16 mm are the centers of the light emitting surfaces 22a of the second LED chip 22 from the left in FIG. The center of the light emitting surface 22a is the center of the light emitting surface 22a of the fourth LED chip 22. Thus, the color difference from the reference point PO is a small value at the center of each light emitting surface 22a of the LED chip 22. However, at a location between two LED chips 22 adjacent to each other, the color difference from the reference point PO gradually increases as it approaches the midpoint of the two LED chips 22. Therefore, the middle point between the two LED chips 22 has the largest color difference from the reference point PO.

  As the values of Δcx and Δcy are increased, the emitted light is more reddish than the reference point PO. Therefore, in the light emitting module 50 which concerns on the comparative example 1, it turns out that the emitted light is reddish between the adjacent LED chips 22. FIG. For this reason, in the light emitting module 50 which concerns on the comparative example 1, it turns out that the color of emitted light is not uniform.

  FIG. 5 is a cross-sectional view of the light emitting module 50 for explaining a mechanism in which color unevenness occurs in the first comparative example. Hereinafter, the above-described blue phosphor and yellow-green phosphor included in the first phosphor layer 24 and the phosphor layer 52 are referred to as “blue phosphor 80” and “yellow-green phosphor 82”, and the second phosphor layer. 26 and the phosphor layer 52 included in the phosphor layer 52 is referred to as a “red phosphor 84”.

  In the light emitting module 50 according to the comparative example 1, the phosphor layer 52 includes the blue phosphor 80, the yellow-green phosphor 82, and the red phosphor 84. For this reason, as shown in FIG. 5, the light emitted from the LED chip 22 with a short optical path length, that is, the light emitted from the position close to the LED chip 22 on the emission surface 52 a is caused by the blue phosphor 80. The possibility that the blue light after wavelength conversion and the yellow-green light after wavelength conversion by the yellow-green phosphor 82 are wavelength-converted again by the red phosphor 84 to become red light is relatively low. On the other hand, the light emitted from the LED chip 22 with a long optical path length, that is, the light emitted from a position far from the LED chip 22 in the emission surface 52a is blue light after wavelength conversion by the blue phosphor 80. The probability that yellow-green light after wavelength conversion by the yellow-green phosphor 82 is wavelength-converted again by the red phosphor 84 to become red light is higher than light emitted from a position close to the LED chip 22. For this reason, as shown in FIG. 4, in the light emitting module 50 according to the comparative example 1, it is considered that the emitted light is reddish between the adjacent LED chips 22. Note that the light emitted from the LED chip 22 and having a long optical path length means that light emitted from the blue phosphor 80 or the yellow-green phosphor 82 is directly emitted from a position far from the LED chip 22 on the emission surface 52a. And light emitted from the blue phosphor 80 and the yellow-green phosphor 82 once reflected on the mounting surface 20a and then emitted from a position far from the LED chip 22 on the emission surface 52a.

  FIG. 6 is a diagram illustrating measurement results when the chromaticity is measured while moving the measurement point from the reference point PO in the measurement direction D1 in the light emitting module 10 according to the first embodiment. Also in FIG. 6, the locations where the distance from the reference point PO is 0 mm, 8 mm, and 16 mm are the center of the light emitting surface 22a of the second LED chip 22 from the left in FIG. 3B, and the third LED chip 22 Becomes the center of the light emitting surface 22a of the fourth LED chip 22. However, as shown in FIG. 6, Δcx and Δcy are substantially uniform regardless of the distance from the reference point PO. Therefore, it can be seen that in the light emitting module 10 according to Example 1, color unevenness hardly occurs.

  FIG. 7 is a cross-sectional view of the light emitting module 10 for explaining a mechanism in which uneven color is suppressed in the first embodiment. As shown in FIG. 7, the second phosphor layer 26 is formed to cover the light emitting surface 22a. For this reason, a part of the light emitted from the light emitting surface 22 a is converted into red light by the red phosphor 84 of the second phosphor layer 26. Thus, the converted red light and unconverted light are emitted from the emission surface 26 a of the second phosphor layer 26 to the first phosphor layer 24. The light emitted from the second phosphor layer 26 enters the first phosphor layer 24 from the incident surface 24b in contact with the emission surface 26a.

  The blue phosphor 80 and the yellow-green phosphor 82 included in the first phosphor layer 24 are not excited by red light. For this reason, red light out of the light incident on the first phosphor layer 24 is directly emitted from the emission surface 24a.

  Of the light incident on the first phosphor layer 24, the light that has not been converted in the second phosphor layer 26 is converted into blue light and yellow-green light by the blue phosphor 80 and the yellow-green phosphor 82, respectively. As described above, the yellow-green phosphor 82 is not easily excited by the blue light emitted from the blue phosphor 80. From the above, the light traveling toward the emission surface 24a inside the first phosphor layer 24 is compared with the possibility that the light once wavelength-converted by any phosphor is wavelength-converted again by another phosphor. Compared to Example 1, it is much lower.

  Inside the first phosphor layer 24, the blue phosphor 80 and the yellow-green phosphor 82 emit blue light and yellow-green light to Lambertian, respectively. Therefore, light is emitted from the blue phosphor 80 and the yellow-green phosphor 82 not only toward the emission surface 24a but also toward the mounting surface 20a. This light is reflected by the mounting surface 20a and converted to red light emitted to Lambertian by the second phosphor layer 26, and is mainly between the adjacent LED chips 22 and other than the vertically upper side of the LED chip 22, the emission surface 24a. Exits from. On the other hand, as described above, the direct light from the light emitting surface 22a is not reachable on the mounting surface 20a, but the second light that is wavelength-converted by the first phosphor layer 24 and that is directed to the mounting surface 20a is located second. A second layer 26c of the phosphor layer 26 is provided.

  Specifically, the second phosphor layer 26 is located in a non-direct irradiation region closer to the mounting surface 20a than the plane including the light emitting surface 22a in the region between the plurality of LED chips 22 when viewed from the light emitting surface 22a side. Part is formed. For this reason, a part of the light toward the mounting surface 20a out of the blue light and yellow-green light emitted after wavelength conversion by the first phosphor layer 24 is mainly caused by the red phosphor 84 included in the second layer 26c. Converted to red light. In this way, by forming the second phosphor layer 26 including the red phosphor 84 in the non-direct irradiation region, after facing the mounting surface 20a in the first phosphor layer 24, other than vertically above the LED chip 22 The light emitted from the emission surface 24a can also be light in which blue light, yellow-green light, and red light are appropriately mixed. From the above, light in which blue light, yellow-green light, and red light are appropriately mixed can be emitted from the light emitting surface 24a in the vertically upper portion of the light emitting surface 22a and in portions other than the vertically upper portion. . For this reason, color unevenness can be reduced over the whole emission surface 24a.

(Example 2)
FIG. 8A is a front sectional view of the light emitting module 100 according to the second embodiment, and FIG. 8B is a top view of the light emitting module 100 according to the second embodiment. Hereinafter, the same parts as those in the first embodiment are denoted by the same reference numerals and the description thereof is omitted.

  The light emitting module 100 includes an LED unit 102 and a phosphor unit 104. The LED unit 102 includes a substrate 106 and an LED chip 22. The substrate 106 has a square outer shape. One LED chip 22 is mounted in the center of the substrate 106.

  The phosphor unit 104 includes a first phosphor layer 110 and a second phosphor layer 112. The first phosphor layer 110 includes a blue phosphor (not shown) and a yellow-green phosphor (not shown). The blue phosphor and the yellow-green phosphor contained in the first phosphor layer 110 are the same as those contained in the first phosphor layer 24 in the first embodiment.

  The second phosphor layer 112 includes a red phosphor (not shown). The red phosphor contained in the second phosphor layer 112 is the same as that contained in the second phosphor layer 26 in the first embodiment. The second phosphor layer 112 was directly applied to the mounting surface 106a of the substrate 106 on which the LED chip 22 was mounted.

  Specifically, first, a red phosphor paste including the red phosphor 84 was prepared. The method for adjusting the red phosphor paste is the same as in Example 1. The red phosphor paste thus adjusted was applied to the mounting surface 106a of the substrate 106 on which the LED chip 22 was mounted. At this time, similarly to Example 1, the second phosphor layer 112 was applied so that the light emitting direction from the light emitting surface 22a, that is, the thickness of the layer formed on the light emitting surface 22a was 80 μm. In addition, the 2nd fluorescent substance layer 112 may be formed so that the thickness of the layer formed on the light emission surface 22a may become any value of 20-200 micrometers.

  The first phosphor layer 110 was further applied on the upper surface of the second phosphor layer 112. Specifically, a mixed phosphor paste including blue phosphor 80 and yellow-green phosphor 82 was first prepared. The method for adjusting the mixed phosphor paste is the same as in Example 1. The mixed phosphor paste thus prepared was applied over the already applied red phosphor paste. At this time, the thickness of the first phosphor layer 110 was 4 mm. The thickness of the first phosphor layer 110 may be any value between 0.5 and 18 mm, more preferably any value between 0.5 and 5 mm.

  Thus, the second phosphor layer 112 and the first phosphor layer 110 were laminated in this order from the mounting surface 106a of the substrate 106. At this time, as shown in FIG. 8B, the second phosphor layer 112 and the first phosphor layer 110 were laminated so that a circle with a radius of 5 mm centered on the center of the light emitting surface 22a was the outer shape. Needless to say, the radius of the circle is not limited to 5 mm, and the outer shape of the second phosphor layer 112 and the first phosphor layer 110 is not limited to a circle. The second phosphor layer 112 is applied to the mounting surface 106a so as to have a substantially uniform thickness, whereas the first phosphor layer 110 is hemispherical on the emission surface 112a of the second phosphor layer 112. It was applied as follows.

  The light emitting module 100 according to Example 2 was turned on and the chromaticity distribution was measured. The measurement of chromaticity was started from the center of the LED chip 22 as a reference point PO. As shown in FIG. 8B, chromaticity measurement is repeated while gradually moving the measurement point from the reference point PO toward the outer edge of the phosphor unit 104, and the measurement point reaches the outer edge of the phosphor unit 104. Until the measurement was completed. Hereinafter, the moving direction of the measurement point is referred to as a measurement direction D2.

  FIG. 9A is a front sectional view of the light emitting module 150 according to Comparative Example 2, and FIG. 9B is a top view of the light emitting module 150 according to Comparative Example 2. Hereinafter, the same parts as those in the above-described embodiment and comparative example are denoted by the same reference numerals, and the description thereof is omitted.

  The light emitting module 150 includes an LED unit 102 and a phosphor layer 152. The phosphor layer 152 includes a red phosphor, a yellow-green phosphor, and a blue phosphor used in the light emitting module 10. The method of producing the mixed phosphor paste for forming the phosphor layer 152 is the same as that in Comparative Example 1. The mixed phosphor paste thus adjusted was applied onto the mounting surface 106a of the substrate 106 to form the phosphor layer 152. At this time, the thickness of the phosphor layer 152 was 4 mm.

(Experimental result 2)
FIG. 10 is a diagram illustrating a measurement result when the chromaticity is measured while moving the measurement point from the reference point PO in the measurement direction D2 in the light emitting module 150 according to the comparative example 2. Δcx and Δcy on the vertical axis indicate the amount of change in the color coordinates (cx, cy) in the CIE chromaticity coordinates with the CIE chromaticity at the reference point PO as a reference value.

  In FIG. 10, the color difference from the reference point PO gradually increases as the distance from the reference point PO increases. Therefore, it can be seen that in the light emitting module 150 according to the comparative example 2, as the distance from the reference point PO increases, the light emitting module 150 is more reddish than the reference point PO, and light of uniform color cannot be emitted.

  Thus, the mechanism by which the color of the emitted light is non-uniform is the same as in Comparative Example 1. That is, the light emitted from the light emitting surface 22a of the LED chip 22 and emitted from the reference point PO with a short optical path length is the blue light and yellow green light emitted after wavelength conversion by the blue phosphor 80 and the yellow-green phosphor 82. The possibility of wavelength conversion to red light again by the red phosphor 84 is low.

  On the other hand, the light emitted from the light emitting surface 22a of the LED chip 22 has directivity that travels vertically upward from the light emitting surface 22a. The light emitted from the portion having a large distance from the reference point PO is light that has traveled in various directions while being wavelength-converted by the phosphor inside the phosphor layer 152. For this reason, the farther the light emission point is from the reference point PO, the longer the light follows the long path in the phosphor layer 152. Therefore, the farther the light emission point is from the reference point PO, the blue light and yellow-green light emitted by wavelength conversion by the blue phosphor 80 and the yellow-green phosphor 82 are converted into red light again by the red phosphor 84. Is more likely. In this way, reddish light is emitted as the light is emitted farther from the reference point PO.

  FIG. 11 is a diagram illustrating a measurement result when the chromaticity is measured while moving the measurement point from the reference point PO in the measurement direction D2 in the light emitting module 100 according to the second embodiment. As shown in FIG. 11, Δcx and Δcy are substantially uniform regardless of the distance from the reference point PO. Therefore, it can be seen that in the light emitting module 100 according to Example 2, the color unevenness hardly occurs.

  The mechanism for making the color of the emitted light uniform in this way is the same as in the first embodiment. That is, the light that travels toward the emission surface 110a inside the first phosphor layer 110 may be subjected to wavelength conversion of light once wavelength-converted by one of the phosphors with another phosphor. Compared to 2, it is much lower.

  Further, of the blue light and yellow-green light emitted after wavelength conversion by the first phosphor layer 110, a part of the light traveling toward the mounting surface 106a is included in the non-direct irradiation region on the mounting surface 106a side from the light emitting surface 22a. It is converted into red light by the red phosphor 84. In this way, by forming the second phosphor layer 112 including the red phosphor 84 in the non-direct irradiation region, the first phosphor layer 110 is directed to the mounting surface 106a and then other than vertically above the LED chip 22. The light emitted from the emission surface 110a can also be light in which blue light, yellow-green light, and red light are appropriately mixed. As described above, light in which blue light, yellow-green light, and red light are appropriately mixed can be emitted from the emission surface 110a at a portion vertically above the light emitting surface 22a and at portions other than vertically above. . For this reason, color unevenness can be reduced over the entire emission surface 110a.

  FIG. 12 is a diagram illustrating the color rendering index Ra of each of the light emitting module 100 according to Example 2 and the light emitting module 150 according to Comparative Example 2. As described above, the light emitting module 100 according to Example 2 has a color rendering index Ra of more than 80, and can achieve higher color rendering than the light emitting module 150 according to Comparative Example 2. Therefore, according to the light emitting module 100 which concerns on Example 2, the light of a uniform color can be radiate | emitted, implement | achieving high color rendering properties.

  The present invention is not limited to the above-described embodiments, and an appropriate combination of the elements of each embodiment is also effective as an embodiment of the present invention. Various modifications such as design changes can be added to each embodiment based on the knowledge of those skilled in the art, and embodiments to which such modifications are added can also be included in the scope of the present invention.

  In a modification, the second phosphor layer and the first phosphor layer are stacked without mounting an LED chip or an electrode for electrically connecting the LED chip and the substrate in advance on the substrate. Specifically, for example, the red phosphor paste is printed on the substrate part other than the LED chip and the electrode part using stencil printing (screen printing) so that the coating thickness becomes 20 to 200 μm. The concentration of the red phosphor paste, the resin that seals the red phosphor, and the thickness of the second phosphor layer are the same as those in Example 1 or 2 described above.

  Further, as a sealing material, a glass system (borosilicate system, aluminosilicate system, soda borosilicate system, etc.) or various low melting glass systems may be used. In this case, the red phosphor 84 is sealed so as to have a concentration of 0.5 to 15 vol%, and the thickness is 20 to 600 μm (more preferably 20 to 200 μm). May be.

  Further, for example, the LED chip, the electrode portion, and the like may be masked in advance and the red phosphor paste may be coated. Coating methods are air doctor coater, blade coater, rod coater, knife coater, squeeze coater, impregnated coater, reverse roll coater, transfer roll coater, gravure coater, kiss coater, cast coating, dip coating, spray coating, slot orifice coating, calendar Coating, electrostatic powder coating, electrodeposition coating, powder electrodeposition coating, extrusion coating, spin coating, and the like are possible, and various methods can be taken according to the viscosity and production cost of the red phosphor paste.

  Next, a method for forming the second phosphor layer including the red phosphor 84 on the LED chip will be described. First, a red phosphor paste having a phosphor concentration adjusted to 0.5 to 10 vol% using a silicone resin such as dimethyl silicone, phenyl silicone, or acrylic silicone, a sol-gel (silica, titania, etc.) resin, or a fluoropolymer resin. Adjust and apply dispense, mold, or semi-cured or cured in sheet form in advance. Further, a glass system (borosilicate system, aluminosilicate system, soda borosilicate system, etc.) or various low melting glass systems are used as the sealing material, and the phosphor is sealed so that the phosphor concentration is 0.5 to 10 vol%. After processing to the size which covers a chip surface, it can also adhere on an LED chip. The thickness of the 2nd fluorescent substance layer 26 shall be 20-200 micrometers.

  When the mixed layer of the red phosphor 84, the blue phosphor 80, and the yellow-green phosphor 82 is formed as in the comparative example 1 or 2, the same method as that for forming the layer of only the red phosphor 84 is used. Can be formed. When the mixed layer is formed on the LED chip, an LED light emitting module in which the entire light emitting portion emits light in a uniform color can be produced.

  After the red phosphor 84 layer is formed on the LED chip, as described above, it is semi-cured or cured under conditions suitable for the resin using the red phosphor 84 layer on the substrate. The same applies after the mixed layer of the red phosphor 84, the blue phosphor 80, and the yellow-green phosphor 82 is formed in order to obtain the light emitting module according to the comparative example 1 or 2.

  When a glass sealing material is used, it is cured according to the curing conditions of the adhesive. Thereafter, a blue phosphor 80 adjusted to a phosphor concentration of 0.5 to 8 vol% using a silicone resin such as dimethyl silicone, phenyl silicone, or acrylic silicone, a sol-gel (silica, titania) resin, or a fluoropolymer resin, yellow The mixed resin paste of the green phosphor 82 is adjusted. A blue phosphor 80 and yellow-green phosphor 82 mixed resin paste is dispensed on the substrate coated with the second phosphor layer, or molded using various molds. Similarly, the blue phosphor 80 and the yellow-green phosphor 82 are applied on the LED chip coated with the red phosphor 84 layer and on the LED chip coated with the red phosphor 84, the blue phosphor 80, and the yellow-green phosphor 82 mixed layer. The mixed resin paste is dispensed or molded using various molds. At this time, the coating thickness and the mold thickness are 0.5 to 18 mm (more preferably 0.5 to 5 mm).

  Thereafter, the mixed layer of the blue phosphor 80 and the yellow-green phosphor 82 is cured under conditions suitable for the used resin. Further, as the sealing material, a glass system (borosilicate system, aluminosilicate system, soda borosilicate system, etc.) and various low melting glass systems can be used, and a mixture of blue phosphor 80 and yellow green phosphor 82 is used as the phosphor. Sealed to a concentration of 0.1 to 10 vol% (more preferably 0.5 to 10 vol%) and processed into a predetermined size of 0.5 to 18 mm thickness (more preferably 0.5 to 5 mm thickness) A phosphor-encapsulated glass (plate-shaped, molded product using various molds) may be produced. Further, the phosphor-encapsulated glass is applied on the substrate coated with the red phosphor 84 layer and on the LED chip coated with the red phosphor 84 layer or the red phosphor 84, the blue phosphor 80, and the yellow-green phosphor 82 mixed layer. It may be glued.

(Modification of phosphor used for second phosphor layer)
The phosphor used in the second phosphor layer described above is not limited to the red phosphor, but may be any phosphor that uses at least part of the light emitted from the phosphor contained in the first phosphor layer as excitation light. Good. For example, a green phosphor that absorbs light of a blue phosphor or a yellow phosphor contained in the first phosphor layer may be used as the second phosphor layer.

  Moreover, the phosphor contained in the second phosphor layer may be one type or plural types. For example, in order to set the chromaticity and color rendering properties to desired values, a red phosphor and a green phosphor that uses at least a part of the light of the blue phosphor as excitation light may be mixed and used.

In addition, examples of the green phosphor include phosphors represented by the following general formulas. Note that the phosphors shown below are examples, and other green phosphors may be used.
A phosphor represented by the general formula (Si, Al) ₆ (O, N) ₈ : Eu (β sialon).
General formula (Sr _1-xy , Ca _x ) Ga ₂ (S _z , Se _1-z ) ₄ : Eu _y ²⁺ (where x, y, z are 0 ≦ x <1, 0 <y < 0.2, 0 <x + y ≦ 1, and 0 <z ≦ 1)).
Formula _{(Sr 1-x-y-} z, Ca x, Ba y, Mg z) 2 SiO 4: Eu w 2+ ( wherein, x, y, z, w is, 0 <x <1,0.5 <Y <1, 0 <z <1, 0.03 <w <0.2, 0 <x + y + z + w <1 is satisfied.)
A phosphor represented by the general formula Y ₃ (Al _1-x , Ga _x ) ₅ O ₁₂ : Ce (0 <x ≦ 1).
A phosphor represented by the general formula CaSc ₂ Si ₃ O ₁₂ : Ce.
A phosphor represented by the general formula CaSc ₂ O ₄ : Eu.
A phosphor represented by the general formula (Ba, Sr) ₃ Si ₂ O ₃ N: Eu ²⁺ .
A phosphor represented by the general formula NaBaScSi ₂ O ₇ : Eu ²⁺ .

(Phosphor concentration distribution in the second phosphor layer)
The above-mentioned second phosphor layer does not particularly take into consideration the concentration distribution of the contained phosphor. Therefore, there is room for improvement regarding the uniformity of the color of light emitted from the light emitting module. FIG. 13A is a diagram schematically showing variations in the color of light emitted from the light emitting module when the concentration distribution of the phosphors in the second phosphor layer is uniform, and FIG. 13B is a diagram illustrating the second fluorescence. It is a figure which shows typically the dispersion | variation in the color of the irradiation light of the light emitting module at the time of changing the density | concentration of the fluorescent substance of a body layer.

  As shown in FIG. 13A, when the concentration of the red phosphor 84 included in the second phosphor layer 26 on the substrate 20 is uniform, the irradiation light emitted from the LED chip 22 is relatively strong. Table 1 shows the qualitative strength of each color phosphor light in R1 and in the region R2 around the region R1 where the irradiation light emitted from the LED chip 22 is relatively weak.

  As shown in Table 1, in each color phosphor color light, the region R1 where the irradiation light of the LED chip 22 is strong is stronger than the region R2 where the irradiation light of the LED chip 22 is weak. Further, as shown in FIG. 13A, since the irradiation light of the LED chip 22 is radial, the range in which the red phosphor 84 included in the second phosphor layer 26 close to the LED chip 22 is excited is the LED chip. The range is narrower than the range in which the blue phosphor 80 and the yellow-green phosphor 82 included in the first phosphor layer 24 far from 22 are excited. Therefore, the red phosphor light in the region R2 is relatively weaker than the blue phosphor light and the yellow-green phosphor light. For this reason, the region R1 and the region 2 have not only uneven brightness but also color variations.

  Therefore, as shown in FIG. 13B, the above-described color variation can be suppressed by changing the concentration of the red phosphor 84 depending on the location in the second phosphor layer 26. Specifically, the concentration of the red phosphor 84 in the second phosphor layer 26 is higher in the region 26e far from the chip where the irradiation light is weaker than in the region 26d immediately above the chip where the irradiation light of the LED chip 22 is strong. To. More preferably, the concentration of the red phosphor 84 in the region 26e1 included in the region R2 where the irradiation light is weak in the region 26e may be increased.

  As shown in FIG. 13B, when the concentration of the red phosphor 84 included in the second phosphor layer 26 on the substrate 20 is higher in the region 26e than in the region 26d, the light is emitted from the LED chip 22. Table 2 shows the qualitative strength of each color phosphor light in the region R1 where the irradiation light is strong and the region R2 around the region R1 where the irradiation light emitted from the LED chip 22 is weak.

  As shown in Table 2, in each color phosphor color light, the region R1 where the irradiation light of the LED chip 22 is strong is stronger than the region R2 where the irradiation light of the LED chip 22 is weak. Further, as shown in FIG. 13B, since the irradiation light of the LED chip 22 is radial, the range in which the red phosphor 84 included in the second phosphor layer 26 close to the LED chip 22 is excited is the LED chip. The range is narrower than the range in which the blue phosphor 80 and the yellow-green phosphor 82 included in the first phosphor layer 24 far from 22 are excited. However, in the region 26e of the second phosphor layer 26 included in the region R2, since the concentration of the red phosphor 84 is high, light equivalent to blue phosphor light or yellow-green phosphor light is irradiated. For this reason, there is no significant difference in the proportion of the phosphor light of each color between the region R1 and the region 2, and the color uniformity is improved.

  In addition, the distribution of the phosphor concentration in the second phosphor layer described above is an example, and is appropriately determined depending on the light distribution of the LED chip, the shape of each phosphor layer, the type and concentration of the phosphor included in each phosphor layer, and the like. Is to be selected.

(Modification of the shape of the second phosphor layer)
In the second phosphor layer 26 described above, for example, as shown in FIG. 7, the thickness of the first layer 26b is constant. However, the thickness of the first layer does not need to be constant over the entire surface of the substrate, and the shape may be appropriately selected depending on the light distribution required for the LED module, the phosphor concentration of each phosphor layer, and the like.

  FIG. 14 is a partial cross-sectional view of the light emitting module 210 showing a modification of the second phosphor layer. As shown in FIG. 14, the first layer 26b of the second phosphor layer 26 is formed only immediately above and in the vicinity of the LED chip 22, and the first layer 26b is not formed in other regions. Thus, by devising the shape, the amount of red phosphor light can be appropriately controlled in the area directly above and near the area where the direct light from the LED chip 22 is strong, and in other areas. As a result, the color uniformity of the irradiation light of the light emitting module 210 is improved.

  Next, some specific examples of the shape of the second phosphor layer will be described. FIG. 15A to FIG. 15F are a perspective view, a cross-sectional view, or a top view showing an example of the shape of the second phosphor layer. The second phosphor layer 160 shown in FIG. 15A has a plate (cuboid) shape. The second phosphor layer 162 shown in FIG. 15B has a semi-cylindrical shape. The second phosphor layer 164 shown in FIGS. 15C and 15D has a semicircular cross section and a circular dome shape when viewed from above. In addition, the figure shown in FIG.15 (d) is a top view seen from the arrow A direction of FIG.15 (c). The second phosphor layer 166 shown in FIGS. 15 (e) and 15 (f) has a mountain shape with a recessed center in a cross-sectional view, and has a circular lens shape in a top view. In addition, the figure shown in FIG.15 (f) is a top view seen from the arrow A direction of FIG.15 (e). The shape of the second phosphor layer is not limited to that illustrated.

  Moreover, you may comprise a 2nd fluorescent substance layer combining the above shapes. FIG. 16 is a partial cross-sectional view of the light emitting module 220 showing a modification of the second phosphor layer. The light emitting module 220 has a dome shape as shown in FIG. 15C directly above the LED chip 22, and the other part has a plate-like second phosphor layer 26 as shown in FIG. 15A. ing. By using the second phosphor layer 26 combined with such a shape, the amount of red phosphor light is appropriately adjusted in the region directly above and near the region where the direct light from the LED chip 22 is strong, and in other regions. Can be controlled. As a result, the color uniformity of the irradiation light of the light emitting module 220 is improved.

(Modification of the shape of the phosphor layer)
Similar to the shape of the second phosphor layer described above, several examples of the shape of the entire phosphor layer including the first phosphor layer and the second phosphor layer will be exemplified. FIG. 17A and FIG. 17B are perspective views illustrating a modification of the entire phosphor layer in the light emitting module 10 according to the first embodiment. FIG. 18A to FIG. 18E are a perspective view, a cross-sectional view, or a top view illustrating a modification of the entire phosphor layer in the light emitting module 100 according to the second embodiment.

  The phosphor layer 168 shown in FIG. 17A has a plate (cuboid) shape. The phosphor layer 170 shown in FIG. 17B has a semi-cylindrical shape. The phosphor layer 172 shown in FIG. 18A has a plate (cuboid) shape. The phosphor layer 174 shown in FIGS. 18B and 18C has a semicircular cross section and a circular dome shape when viewed from above. In addition, the figure shown in FIG.18 (c) is a top view seen from the arrow A direction of FIG.18 (b). The phosphor layer 176 shown in FIGS. 18D and 18E has a mountain shape with a recessed center in a cross-sectional view, and has a circular lens shape in a top view. In addition, the figure shown in FIG.18 (e) is a top view seen from the arrow A direction of FIG.18 (d).

  Here, as for the preferable dimension of each fluorescent substance layer shown in FIG.17, FIG.18, height H is about 0.5-18 mm, and width W is about 0.5-20 mm. In addition, the shape of the whole fluorescent substance layer is not limited to what was illustrated.

(Distance between LED chips and driving current in the light emitting module according to Example 1)
When a plurality of LED chips 22 are mounted as in the light emitting module 10 according to the first embodiment, an appropriate interval between the chips can be changed depending on a current value flowing through one LED chip 22. This is because if the interval for mounting the plurality of LED chips 22 becomes wider than the appropriate interval, bright portions and dark portions are generated in the light emitting module 10 and uniform light emission does not occur. This is because the number of LED chips 22 increases and the cost increases.

  Therefore, the relationship between the distance between the LED chips 22 and the optimum current value flowing through the chips may be the relationship shown below. For example, when the distance between chips is 0.5 to 5 mm, the drive current is in the range of 10 to 30 mA, and when the distance between chips is 3.0 to 20 mm, the drive current is in the range of 20 to 300 mA, and the distance between chips. Is 10 to 50 mm, the driving current is 100 to 1000 mA, and when the distance between chips is 30 to 100 mm, the driving current is preferably set in the range of 300 to 1500 mA. Specifically, when the current value flowing through the LED chip 22 is 100 mA, the distance between the chips is preferably about 8 mm. By setting the distance between the chips and the drive current in such a relationship, uniform light emission of the light emitting module can be realized while suppressing the number of LED chips.

(Suppression of leakage light from the second phosphor layer)
If the second phosphor layer 112 under the first phosphor layer 110 is exposed from the side surface as in the light emitting module 100 shown in FIG. 8, the following phenomenon may occur.
(1) At the time of non-lighting, the color (for example, red) of the second phosphor layer 112 becomes strong only on the outer periphery of the surface where the second phosphor layer 112 is in contact with the substrate 106, and it looks like a ring.
(2) Even during lighting, depending on the thickness and concentration of the second phosphor layer 112, the color (for example, red) of the second phosphor layer 112 increases only at the outer periphery of the surface where the second phosphor layer 112 is in contact with the substrate. , It may look like a ring.

  Therefore, in order to suppress such a phenomenon, the following configuration has been devised. FIG. 19A is a cross-sectional view of the light emitting module 230 in which the side surface of the second phosphor layer is covered with the first phosphor layer, and FIG. 19B is directed outward at the outer peripheral portion of the second phosphor layer. FIG. 19C is an enlarged view of a region C shown in FIG. 19B, and FIG. 19D is a cross-sectional view of the light emitting module 240 in which the thickness of the second phosphor layer is reduced. It is sectional drawing of the light emitting module 250 which reduced the thickness of the 2nd fluorescent substance layer toward the outer side in the outer peripheral part of the 2nd fluorescent substance layer to show. In addition, in each figure, about the member similar to FIG. 8, the same code | symbol is attached | subjected and description is abbreviate | omitted suitably.

  In the light emitting module 230 illustrated in FIG. 19A, the first phosphor layer 110 is provided so as to cover the outer peripheral side surface 178 a of the second phosphor layer 178. That is, the first phosphor layer 110 directly covers a part of the mounting surface 106 a of the substrate 106. Thereby, since the outer peripheral side surface 178a of the second phosphor layer 178 is not exposed, it is suppressed that the color (for example, red) of the second phosphor layer 178 looks like a ring at the time of non-lighting or lighting. The distance d1 from the outer peripheral side surface 178a of the second phosphor layer 178 to the surface of the first phosphor layer 110 is preferably about 0.1 to 3 mm. If the distance d1 is less than 0.1 mm, the color (for example, red) of the second phosphor layer 178 may appear in a ring shape when not lit or when lit. When the distance d1 exceeds 3 mm, the volume of the second phosphor layer 178 becomes too small, and the redness of the irradiation light of the light emitting module 230 decreases.

  In addition, the light emitting module 240 shown in FIG. 19B has a ring-shaped tapered surface 180a in which the thickness of the second phosphor layer 180 is reduced toward the outside in the outer peripheral portion of the second phosphor layer 180. The width w1 of the tapered surface is preferably about 0.1 to 3 mm. In addition, the light emitting module 250 shown in FIG. 19D has a ring-shaped tapered surface 182a in which the thickness of the second phosphor layer 182 is reduced toward the outside in the outer peripheral portion of the second phosphor layer 182. The outer edge portion 182b of the tapered surface 182a is located inside the surface of the first phosphor layer 110, and the second phosphor layer 182 is not exposed to the outside. Therefore, in the light emitting module 240 and the light emitting module 250, it is suppressed that the color (for example, red) of a 2nd fluorescent substance layer looks like a ring shape at the time of non-lighting or lighting.

(Correlation of thickness between first phosphor layer and second phosphor layer)
As shown in FIG. 8, in the second phosphor layer 112, when there is a first layer formed on the emission surface side of the plane including the light emitting surface 22 a of the LED chip 22, the second phosphor layer 112 is on the second phosphor layer 112. If the ratio of the thickness of the first phosphor layer 110 to be formed, that is, the distance to the exit surface 110a and the projected area of the second phosphor layer 112 facing the exit surface 110a differs depending on the direction, light emission occurs. The color of the irradiation light is not uniform depending on the light emission direction of the module 100. In the light emitting module 100 shown in FIG. 8, the aforementioned ratio is greatly different between the vertical direction and the horizontal direction of the LED chip 22.

FIG. 20 is a cross-sectional view showing an example of a light emitting module in which the ratio between the thickness of the first phosphor layer and the projected area of the second phosphor layer is substantially the same in a plurality of directions. In the light emitting module 260 shown in FIG. 20, the distance between the upper surface 184a of the second phosphor layer 184 and the exit surface 110a of the first phosphor layer 110 is L1, and the area of the upper surface 184a of the second phosphor layer 184 (from direction A) The projected area of the second phosphor layer 184 as viewed) is S1, the distance between the side surface 184b of the second phosphor layer 184 and the exit surface 110a of the first phosphor layer 110 is L2, and the side surface 184b of the second phosphor layer 184 is. If the area (projected area of the second phosphor layer 184 as viewed from the direction B) is S2, the following formula (1) may be satisfied.
L1 / S1≈L2 / S2 Formula (1)
Thereby, the dispersion | variation in the color of the irradiation light by the light emission direction of the light emitting module 260 is reduced.

  FIG. 21 is a cross-sectional view showing another example of a light emitting module in which the ratio between the thickness of the first phosphor layer and the projected area of the second phosphor layer is substantially the same in a plurality of directions. The light emitting module 270 shown in FIG. 21 is significantly different from the light emitting module 260 shown in FIG. 20 in that the light emitting module 270 includes a plurality of LED chips 22. However, if it is considered that two light emitting modules 270a and 270b are arranged in parallel with a boundary S including an intermediate point between one LED chip 22 and an adjacent LED chip 22, depending on the light emission direction of the light emitting modules 270a and 270b. In order to make the color of the irradiation light uniform, the same relationship as that of the light emitting module 260 shown in FIG.

  That is, in the light emitting module 270a (270b) shown in FIG. 21, the distance between the upper surface 184a of the second phosphor layer 184 and the exit surface 110a of the first phosphor layer 110 is L1, and the upper surface 184a of the second phosphor layer 184 is The area (projected area of the second phosphor layer 184 viewed from the direction A) is S1, the distance between the side surface 184b of the second phosphor layer 184 and the boundary S is L2, and the area of the side surface 184b of the second phosphor layer 184 ( When the projected area of the second phosphor layer 184 when viewed from the direction B is S2, it is preferable to satisfy the above-described formula (1). Thereby, the dispersion | variation in the color by the light emission direction of the light emitting module 270 is reduced.

  10 LED module, 12 LED unit, 14 phosphor unit, 20 substrate, 20a mounting surface, 22 LED chip, 22a light emitting surface, 22b side surface, 24 first phosphor layer, 24a emitting surface, 26 second phosphor layer, 26b 1st layer, 26c 2nd layer, 50 light emitting module, 52 phosphor layer, 52a emission surface, 80 blue phosphor, 82 yellow green phosphor, 84 red phosphor, 100 light emitting module, 102 LED unit, 104 phosphor unit , 106 substrate, 106a mounting surface, 110 first phosphor layer, 110a emitting surface, 112 second phosphor layer, 150 light emitting module, 152 phosphor layer, 152a emitting surface.

  INDUSTRIAL APPLICABILITY The present invention can be used for a light emitting module, and in particular, can be used for a light emitting module including a phosphor layer that emits light after wavelength conversion.

Claims (4)

A first phosphor layer;
A second phosphor layer having a longer wavelength of light after wavelength conversion than the first phosphor layer;
With
The first phosphor layer is formed in the irradiation region of the light from the light emitting element, converts the wavelength of the light from the light emitting element and emits it from the emission surface,
At least a part of the second phosphor layer is formed in a predetermined region where light is not irradiated from the light emitting element and light is irradiated from the first phosphor layer, and a portion formed in the predetermined region is the first phosphor. A light emitting module, wherein the light from the layer is wavelength-converted and emitted from the emission surface through the first phosphor layer. At least a part of the second phosphor layer is formed between a plane including the light emitting surface of the light emitting element and a mounting surface of the substrate on which the light emitting element is mounted,
2. The light emitting module according to claim 1, wherein the first phosphor layer is formed on the light emitting direction side of the light emitting surface with respect to the second phosphor layer.   The light emitting module according to claim 2, wherein the second phosphor layer is formed from the mounting surface to the light emitting direction side of the light emitting surface to cover the light emitting surface. A plurality of the light emitting elements are arranged so that each light emitting surface is included in one plane while being separated from each other,
The second phosphor layer is formed at least partially on the side opposite to the light emitting direction of the light emitting surface from the plane in the region between the plurality of light emitting elements when viewed from the light emitting surface side.
2. The light emitting module according to claim 1, wherein the first phosphor layer is formed on the light emitting direction side of the light emitting surface with respect to the second phosphor layer.

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